The present invention relates to a zoom lens and an imaging apparatus incorporating the same.
Instead of silver-halide film cameras, digital cameras designed to use such imaging devices as CCDs or CMOSs to take photographs of subjects have gone mainstream. Further, they now have a wide spectrum of categories from the commercial-use, multi-function type to the compact low-end type. In the invention, attention is paid to the low-end type category in particular.
Users of such low-end type digital cameras would enjoy snapping shots over a wide range of scenes anywhere at any time in a convenient fashion. For this reason, preference is given to digital cameras of the type that can well be put away in small-size articles such as the pockets or the like of clothing or bagging, are convenient to carry around, and are slimmed down in the thickness direction and, with this, there is mounting demand for taking lens systems much more reduced in size. There is also demand for wider-angle characteristics in photographic areas; there is increasing demand for zoom lenses that have high zoom ratios and achieve optical performance while getting hold of the angle of view at the wide-angle end.
Known from the following patent publications, there have been zoom lenses capable of helping maintain relatively high zoom ratios. Each of them comprises, in order from its object side, a first lens group of positive refracting power, a second lens group of negative refracting power, a third lens group of positive refracting power and a fourth lens group of positive refracting power, wherein the length of the space held between the adjacent lens groups is varied to obtain variable focal length.
Patent Publication 1: JP(A) 2003-315676
Patent Publication 2: JP(A) 2005-331628
Patent Publication 3: JP(A) 2008-102165
Patent Publication 4: JP(A) 2008-102166
However, although the inventions set forth in Patent Publications 1 to 4 are suitable for slimming down the zoom lens upon stowed away in a camera body, yet the orthogonal angle of view at the wide-angle end is barely about 65° at most.